US7239590B2 - Write power control method, write power control apparatus and information recording apparatus having the same - Google Patents

Write power control method, write power control apparatus and information recording apparatus having the same Download PDF

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US7239590B2
US7239590B2 US10/654,936 US65493603A US7239590B2 US 7239590 B2 US7239590 B2 US 7239590B2 US 65493603 A US65493603 A US 65493603A US 7239590 B2 US7239590 B2 US 7239590B2
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power
erase
value
target value
pulse
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US20040052179A1 (en
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Yoshiyuki Ishiyama
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Ricoh Co Ltd
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Ricoh Co Ltd
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
    • G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
    • G11B7/1267—Power calibration
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0045—Recording
    • G11B7/00456—Recording strategies, e.g. pulse sequences

Definitions

  • the present invention relates to write power control methods and write power control apparatuses in drive technologies that record information on optical disks such as CD-Rs, CD-RWs, DVD+RWs, and DVD+Rs.
  • Information is recorded on recordable (write once) and rewritable optical disks by applying thereon a dye-based phase change recording material, for example, forming recording marks by irradiating a laser beam while following a groove, and irradiating the laser beam of an erase power so as to erase the recording marks that are previously recorded.
  • a dye-based phase change recording material for example, forming recording marks by irradiating a laser beam while following a groove, and irradiating the laser beam of an erase power so as to erase the recording marks that are previously recorded.
  • a LD laser diode
  • power control methods in optical disk recording include a method of holding each of peak and bottom values of an optical output pulse, calculating a recording base value based on the held peak and bottom values and the level ratio of the recording base value with respect to predetermined peak and bottom values, and controlling the optical output pulse such that the peak value, bottom value, and recording base value approach respective target values (for example, refer to Japanese Laid-Open Patent Application No. 2000-30276).
  • the recording waveform of a laser beam is a multi-pulse waveform of which signal level, having a peak power, an erase power, and a bottom power, is defined by a predetermined switching timing so that best recording quality is achieved.
  • signal level having a peak power, an erase power, and a bottom power
  • a write power control method of controlling a recording pulse of a laser diode including the steps of:
  • the recording pulse is a multi-pulse defined by a peak power, the erase power, and a bottom power; and the erase power, at a time when the multi-pulse is not being output, is used in the step of controlling the erase power.
  • the average signal level of the multi-pulse is measured.
  • the OPC is performed by using predetermined switching timing and the ratio between an amount added to the bottom power to obtain the erase power and an amount added to the erase power to obtain the peak power.
  • the switching timing is determined in advance so as to obtain the best signal levels of the peak power and bottom power and the best recording quality.
  • the measured signal level is set to the target value.
  • the target value is compared with an output level measured during emission of the multi-pulse while recording information, so as to correct the signal levels of the peak power and bottom power.
  • the write power control method when the average value obtained based on the ratio determined by the peak power, the bottom power, and a predetermined strategy is close to the erase power, the ratio of the multi-pulse in sampling the average value may be varied.
  • the value added to the bottom power to obtain the erase power is defined by dividing the difference between the erase power and the average value by the coefficient determined by the strategy, the bottom power, and the ratio between the value added to the erase power to obtain the peak power and the value added to the bottom power to obtain the erase power.
  • the above-described coefficient is “0”, that is, when the average value calculated by using the ratio determined by the peak power, the bottom power, and the strategy is close to the erase power, it is impossible to define a value added to the bottom power to obtain the erase power by using the difference.
  • the present invention aims to perform correction even if such a singular solution is obtained.
  • correction is performed by varying the ratio to a predetermined ratio with which the coefficient does not become “0” at the timing of sampling an average value during emission of the multi-pulse.
  • the write power control method when the erase power falls within a permissible range with respect to the target value in the step of controlling the erase power, in a case where an average value measured in recording information is greater than the target value measured in the OPC, it is possible to perform correction of increasing first and second additional values, and in a case where the average value is smaller than the target value, it is possible to decrease the first and second additional values, the first additional value being added to the erase power to obtain the peak power, and the second additional value being added to the bottom power to obtain the erase power.
  • the average value in emission of the multi-pulse is defined by the difference from the erase power.
  • correction is not performed in a transitional state where the erase power is being controlled to be the target value during erase power control. The correction is performed when the control of the erase power reaches a steady state.
  • the present invention aims to quickly output the set recording power even if the differential efficiency of the laser diode varies due to environmental change.
  • the differential efficiency of a laser diode is calculated and maintained from a value added to the bottom power to obtain the erase power in a steady state where transitional variation in the correction operation does not occur, and the target emission power of the bottom power and erase power. Based on thus obtained differential efficiency, the initial value of the next following recording power setting is calculated.
  • a write power control apparatus including:
  • a target value setting part setting to a target value, a measured value corresponding to an optimum write power in OPC performed before recording information
  • a comparing part comparing the target value with an output level measured in power control
  • the recording pulse is a multi-pulse defined by a peak power, the erase power, and a bottom power; and the erase power, at a time when the multi-pulse is not being output, is used in controlling the erase power.
  • an information recording apparatus including the above-described write power control apparatus.
  • an average signal level of the multi-pulse, corresponding to the optimum write power in the OPC is measured.
  • the OPC is performed by using predetermined switching timing and the ratio between an amount added to the bottom power to obtain the erase power and an amount added to the erase power to obtain the peak power.
  • the switching timing is determined in advance so as to obtain the best signal levels of the peak power and bottom power and the best recording quality.
  • the measured signal level is set to the target value.
  • the target value is compared with an output level measured during emission of the multi-pulse while recording information, so as to correct the signal levels of the peak power and bottom power.
  • FIG. 1 is a block diagram of a write power control apparatus of an optical disk recording apparatus according to the present invention
  • FIG. 2A is a graph showing an IL (Pw versus I) curve and multi-pulse definition
  • FIG. 2B is a graph for explaining ON/OFF control of the switches 10 .
  • FIG. 3 is a schematic diagram showing an averaged PD signal as a result of passing through a LPF
  • FIG. 4 is a flow chart for explaining an operation flow in mount setting according to the present invention.
  • FIG. 5 is a flow chart for explaining an operation flow in power setting according to the present invention.
  • FIG. 6 is a graph showing the variation of driving current at the time when an LD begins emission.
  • FIGS. 7A and 7B are graphs showing variation of differential efficiency of the LD in accordance with environmental change.
  • FIG. 1 is a block diagram of a write power control apparatus of an optical disk recording apparatus according to the present invention.
  • Information is recorded on a recordable or rewritable optical disk 1 by applying thereon a dye-based phase change recording material, for example, forming recording marks by irradiating a laser beam from a laser diode (LD) 2 provided on a pick up that moves while following a groove, and irradiating the laser beam at erase power so as to erase previously recorded recording marks.
  • a recording waveform is defined by a bottom power (Pb) that is the read level in writing, an erase power (Pm) that is the erase level, and a peak power (Pp) that is the recording mark generation level.
  • the laser beam of each of the power values is driven by the current obtained by multiplying a current determined by the LD 2 by the efficiency (differential efficiency) of output light.
  • the drive current is generated through V/I conversion by LD drivers (V/I) 3 .
  • a central processor 4 can increase and decrease the amount of emitted light by controlling the drive voltage applied to the LD drivers 3 via D/A converters (DACs) 5 .
  • Iapc is the current applied until the LD 2 becomes luminous
  • Iread is the current applied after the current Iapc until the laser beam of the bottom power Pb is obtained
  • Ip 2 is the current applied for increasing the level of the laser beam from Pb to Pm
  • Ip 3 is the current applied for increasing the level of the laser beam from Pm to Pp.
  • FIG. 2A shows an IL (Pw versus I) curve for each signal.
  • the central processor 4 performs ON/OFF control of switches 10 (SW 1 and SW 2 ) by using a timing generator 9 capable of generating a predetermined timing so as to vary the current driving the LD 2 , and thereby generating a write pulse.
  • a part of a laser beam from the LD 2 is detected by a PD (photo diode) 6 and converted by an I-V converter (I/V) 7 .
  • the central processor 4 can obtain the signal after the conversion via an A/D converter (ADC) 8 .
  • the optical disk apparatus includes a control system.
  • the control system records data by using recording marks together with recording spaces and maintains the output level of the erase power in a multi-pulse to be a target value by selectively obtaining a part of the LD 2 output beam for recording spaces.
  • the average value is obtained by removing a frequency component from the output of the PD 6 by causing the output to pass through a low-pass filter (LPF) 11 having a sufficiently low pass band.
  • FIG. 3 is a diagram showing an example of a PD signal that has passed through the LPF.
  • FIGS. 4 and 5 show operation flows of the present invention.
  • an optical disk drive determines the manufacturer of the disk from disk information, jitter is determined in advance such that the best jitter is obtained after recording, and a predetermined strategy for generating a light pulse, stored in a memory, is selected.
  • ⁇ and ⁇ are obtained, where ⁇ is the ratio of the current Ip 2 to the current Ip 3 in a multi-pulse for forming a mark having a certain length, and ⁇ is the timing switching ratio between Pp and Pb in a multi-pulse.
  • the current Ip 2 is the current for raising the laser beam emission from Pb to Pm.
  • the current Ip 3 is for raising the laser beam emission from Pm to Pp.
  • ⁇ represents the differential efficiency
  • the peak power, the erase power, and the bottom power are respectively defined as follows.
  • Pp ⁇ ( I read+ Ip 2 +Ip 3)+ A ⁇ Iapc
  • Pm ⁇ ( I read+ Ip 2)+ A ⁇ Iapc
  • Pb ⁇ ( I read)+ A ⁇ Iapc
  • Iread corresponds to the bottom power
  • Ip 2 corresponds to the difference between the erase power and the Iread power.
  • the differential efficiency ⁇ is constant and Iapc supplements A
  • the erase power may be redefined as follows.
  • step S 101 each ratio is obtained from a strategy.
  • step S 102 the write power is set to a lower limit.
  • step S 103 writing is performed and Pm after LPF is sampled and maintained.
  • step S 104 it is determined whether or not Pw is at the lower limit. If the decision result of step S 104 is YES, the process proceeds to step S 105 .
  • step S 105 the write power Pw is increased, and then the process returns to step S 103 .
  • the process of steps S 103 , S 104 , and S 105 is repeated until the decision result of step S 104 becomes NO.
  • step S 106 the write result is evaluated and the optimum Pw is determined. Then, in step S 107 , the coefficient of Pav is calculated. In step S 108 , it is determined whether or not a singular solution is obtained. If the decision result in step S 108 is YES, then the process proceeds to step S 109 . In step S 109 , the ratio in sampling is selected. Then, in step S 110 , writing is performed with the optimum Pw, and Pm after LPF is measured. Thereafter, the process proceeds to step S 111 . When the decision result in step S 108 is NO, the process also proceeds to step S 111 . In step S 111 , Pm of the optimum Pw is set to a target value. In this manner, the initialization ends.
  • Ip 2 and Iread are varied such that an average value Pav sampled at a certain mark length becomes the target value.
  • Iread corresponds to the bottom power
  • Ip 2 corresponds to the difference between the erase power and the read power.
  • the ratio ( ⁇ ) between the respective target values can be applied. That is, Iread can be determined when Ip 2 is determined.
  • the control system performs binary control.
  • the control system for Iapc to Pm is made stable so that a transitional condition of one of them does not affect the other
  • the control system for Iread to Pav is operated.
  • Pm is varied by varying Iread, which is reflected by Iapc.
  • the condition where both Pm and Pav are made stable is waited for while repeating the above-described operation.
  • step S 201 a DAC set value is calculated from ⁇ .
  • step S 202 the target value is calculated from the coefficient of Pav.
  • step S 203 light emission is started in step S 203 , and Pm is sampled in step S 204 .
  • step S 205 it is determined whether or not Pm falls within a permissible value range.
  • step S 206 it is determined whether or not “Pm>the target value” is satisfied.
  • step S 205 When the decision result in step S 205 is YES, the process proceeds to step S 209 , where sampling of Pav is performed. Then, in step S 210 , it is determined whether or not Pav falls within a permissible value range. When the decision result of step S 210 is NO, the process proceeds to step S 211 . In step S 211 , it is determined whether or not “Pav >the target value” is satisfied. When the decision result in step S 211 is YES, Iread (Ip 2 , Ip 3 ) is decreased in step S 212 , and the process returns to step S 209 .
  • step S 211 when the decision result in step S 211 is NO, Iread (Ip 2 , Ip 3 ) is increased in step S 213 , and the process returns to step S 209 .
  • the process of steps S 209 through S 213 is repeated until the decision result of step S 210 becomes YES.
  • step S 210 When the decision result of step S 210 is YES, then ⁇ is recalculated in step S 214 . In this manner, a stable power state is obtained.
  • FIG. 6 shows the case where the current until the LD 2 becomes luminous varies due to environmental variation. Since Pm and Pav are thus varied, Iapc is increased/decreased (controlled) in accordance with the variation of Pm. In this case, since the differential efficiency does not change, if Pm is made stable, Pav is close to the target value. Thus, Pav is not corrected.
  • FIGS. 7A and 7B show cases where the differential efficiency varies.
  • Iapc is increased/decreased (controlled) such that Pm becomes the target value.
  • Pm becomes close to the target value, and Pm is made stable.
  • Iread, Ip 2 , and Ip 3 are the current amounts at the conventional differential efficiencies. Thus, they are different from the expected values.
  • the target value obtained through calculation is compared with Pav obtained by sampling so as to increase/decrease Iread, Ip 2 , and Ip 3 . Further, Iread (and Ip 2 and Ip 3 ) are increased/decreased after Pm is made stable, so that Pav becomes the target value.
  • the power obtained from Iread in the above state is identical with the target value of the read power at the time. Hence, it is possible to make the convergence time in the above-described control process shorter by calculating the differential efficiency from the read power and Iread, and calculating the initial value of the control in power setting of the next time.
  • the present invention when recording is performed under the condition that the erase power in recording spaces is controlled, it is possible to correct the peak power, with respect to the bottom power, to equal the optimum write power.
  • central processor 4 functions as target value setting means, comparing means, and controlling means.

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US10/654,936 2002-09-17 2003-09-05 Write power control method, write power control apparatus and information recording apparatus having the same Expired - Fee Related US7239590B2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007038634A2 (en) * 2005-09-26 2007-04-05 Silicon Core Technology, Inc. Enhanced linearity dvd writing current circuit

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JP4151957B2 (ja) * 2003-05-12 2008-09-17 株式会社リコー チルト制御方法、プログラム及び記録媒体、並びに光ディスク装置
TW200733088A (en) * 2005-07-07 2007-09-01 Koninkl Philips Electronics Nv Estimation of maximum available write power of an optical storage drive
KR100771863B1 (ko) * 2005-09-06 2007-11-01 삼성전자주식회사 기록 광 신호 제어 장치 및 방법
KR100660879B1 (ko) 2005-09-13 2006-12-26 삼성전자주식회사 기록 광 신호 제어 장치 및 방법
JP2007179668A (ja) * 2005-12-28 2007-07-12 Hitachi Ltd 光ディスク記録／再生装置及びその試し書き方法
JP2007323734A (ja) * 2006-05-31 2007-12-13 Toshiba Corp 光ディスク装置及び記録パワー制御方法
KR101339428B1 (ko) * 2009-08-14 2013-12-09 도시바삼성스토리지테크놀러지코리아 주식회사 기록 제어 방법 및 이를 이용한 광 디스크 드라이브

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US5956313A (en) * 1994-09-28 1999-09-21 Ricoh Company, Ltd. Phase-change optical disc recording method and apparatus, and information recording apparatus and recording pre-compensation method
JP2000030276A (ja) 1998-07-09 2000-01-28 Yamaha Corp 光ディスク記録パワー制御方法及び装置
US20020191506A1 (en) 2001-06-15 2002-12-19 Akihiko Okamoto Optical disk recording method, information processing method, optical disk device, information processing device, and controller usable in the optical disk device
US7019273B2 (en) * 2000-11-15 2006-03-28 Ricoh Company, Ltd. Optical information recording employing improved recording power control scheme

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Publication number Priority date Publication date Assignee Title
US5956313A (en) * 1994-09-28 1999-09-21 Ricoh Company, Ltd. Phase-change optical disc recording method and apparatus, and information recording apparatus and recording pre-compensation method
JP2000030276A (ja) 1998-07-09 2000-01-28 Yamaha Corp 光ディスク記録パワー制御方法及び装置
US7019273B2 (en) * 2000-11-15 2006-03-28 Ricoh Company, Ltd. Optical information recording employing improved recording power control scheme
US20020191506A1 (en) 2001-06-15 2002-12-19 Akihiko Okamoto Optical disk recording method, information processing method, optical disk device, information processing device, and controller usable in the optical disk device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007038634A2 (en) * 2005-09-26 2007-04-05 Silicon Core Technology, Inc. Enhanced linearity dvd writing current circuit
WO2007038634A3 (en) * 2005-09-26 2009-04-09 Silicon Core Technology Inc Enhanced linearity dvd writing current circuit

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